Circuit breaker



1957 w. T. ALLEN ET AL 2,814,693

CIRCUIT BREAKER Filed July 15, 1953 4 Sheets-Sheet 1 Q a; g 47 1 VENTO I Nov. 26, 1957 Filed July 15, 1953 W. T. ALLEN ET AL CIRCUIT BREAKER 4 Sheets-Sheet 3 1957 w. T. ALLEN ET AL 2,814,593

' CIRCUIT BREAKER Filed July 15. 1953 4 Sheets-Sheet 4 43 %2 fiffi ,3

W INVENTORS United States Patent O has! crncurr BREAKER Wallace T. Allen and William H. Woods, D earborn, Mich, assignors to Square B Company, Detroit, Mich, a corporation of Michigan Application July 15, 1953, Serial No. 368,061

7 Claims. (Cl. 200-85) This invention relates to a new and improved tripping mechanism for an automatic electric circuit breaker, and more particularly to a tripping mechanism of improved nature operating in response to the electromagnetic effects of overload current flow.

One object of the present invention is the provision of a new and improved magnetic tripping mechanism for circuit breakers which is compact and relatively inexpensive.

Another object is the provision of a tripping mechanism in accordance with the preceding object in which the tripping mechanism is adjustable to operate over a wide range of current values.

Another object is the provision of a tripping mechanism in accordance with the preceding object in which the tripping mechanism may be adjusted to operate at substantially any current value within the range of the particular trip mechanism.

Another object of the invention is the provision of an improved device in accordance with the preceding objects in which an exteriorly operable mechanism is provided for changing the tension of a spring attached to a movable armature such that substantially a linear relationship between the setting of the mechanism and the current required to trip the mechanism exists.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended drawings illustrating certain preferred embodiments in which:

Figure 1 is a plan view of a circuit breaker incorporating the trip mechanism of the present invention in which certain parts are broken away to disclose the interior mechanism.

Figure 2 is a sectional view along the plane of line IIII of Figure 1.

Figure 3 is a view similar to Figure 2 showing the parts in different positions.

Figure 4 is an enlarged, partial sectional view along the line IVIV of Figure 1.

Figure 5 is a partial sectional view along the plane of line V-V of Figure 4.

Figure 6 is a plan view of the terminal-core assembly of the present invention.

Figure 7 is a side view of the mechanism of Figure 6.

The circuit breaker mechanism with which the current responsive trip of this invention is specifically illustrated corresponds generally to the circuit breaker illustrated in the patent to John G. Jackson et a1. 2,426,880, granted September 2, 1947, and forms no part of the present invention, as it will be understood that the current responsive tripping mechanism may be used with any form of releasable circuit breaker mechanism.

In the drawings, there is illustrated a circuit breaker comprising a 'base 1 of insulating material divided into three, separate compartments by insulating walls such as indicated at 2, the whole normally being covered by an insulating cover 3. Upon one end of the base 1 there are mounted three terminal members 4, corresponding 2,814,593 Patented Nov. 26, 1957 to the three compartments of the circuit breaker, by suitable means such as spun over rivets 5. Each of the terminal members 4 projects inwardly into the c0mpartment with which it is associated and carries at its interior end a fixed contact 6. Disposed adjacent to each of the fixed contacts 6 is an arc controlling structure indicated generally at 7 designed to reduce the injurious effect of arcs caused by separation of the movable contacts, to be later described, from the fixed contacts 6.

Referring only to the central compartment of the base 1, there is provided therein a movable contact 8 which is mounted to a contact carrying arm 9. The arm 9 is formed, as shown in Figure l, of two arms 11 and 12 which are pivotally mounted upon a transverse pin 13 which extends between and through suitable apertures in spaced portions of a fixed frame 14, fixedly mounted to the base by suitable studs 10. Also pivotally mounted on the pin 13 is a yoke-shaped operating member 15 having its opposite side walls cut out as at 16 to receive the hubs 17 of an operating handle 18. The handle 18 pivots about hubs 19 in suitable grooves in the frame 14 and the cover 3. Also disposed about the pin 13 is a spring 29 having one portion thereof bearing against the bight of the operating member 15, and a second portion thereof engaging the interiorly projecting portion of the handle 18, as shown in Figures 2 and 3, which serves to properly position the handle.

To the operating member 15 are pivoted a pair of lever arms 21 as by extruded hub portions at 22, and the opposite ends of the lever arms 21 are connected by a transverse pin 23 which is slidably disposed within slots 24 in the arms 11 and 12 of the contact carrying arm 9. Upon hubs 25, extruded from integral side portions of the frame 14, is pivotally mounted a releasable member 26 having a hook portion 27 between which and the pin 23 are disposed tension springs 28.

At the upper end of the circuit breaker, from the view of Figure 1, there is mounted a second terminal connector 31, mounted to the base by stud 32 and comprising a solderless connector unit 33 and an upstanding portion 34. To the interior face of the portion 34 there is welded one end of a suitable strip-type coil 35 of conducting material which surrounds the bight of a generally U-shaped magnetic core 36. The opposite end of the coil 35 is electrically connected to one end of a flexible connector 37, the opposite end of which is electrically connected to the contact arm 9. The core 36 is provided with projecting ears 38 for cooperation with suitable recesses in the base 1. The legs of core 36 are apertured and extending through these apertures is a bar 39 which aids in maintaining the coil 35 in position. As may be seen from Figure 7, the legs of core 36 are provided at their upward, inner corners with non-magnetic inserts 41 for a purpose to be subsequently explained.

Aligned with and adjacent to the upstanding portion 34 is an insulating plate 42 having a centrally disposed aperture therein through which projects the stem of an adjusting means 43. (As shown in Figure 4, cover 3 normally engages plate 42.) The adjusting means comprises a button 44 having an integral, inwardly projecting collar 45 which has integrally mounted thereto (so as to be movable therewith) a hollow shaft 46 interiorly threaded as at 47. The plate 42 and button 44 are pref erably provided with suitable indicia. Against the inwardly facing surface of the plate 42 is a bracket 48 having a suitable aperture through which passes the collar 45. The bracket 48 has integrally formed therewith a stop 49 and a pair of spaced, upstanding ears 51 for a purpose to be subsequently explained. Adjacent the interior surface of the bracket 48 is disposed a fricbe rotatable therewith.

As will be seen particularly from Figures 4 and 5, the washer 52 is cut away over approximately 180 degrees of arc so as to present an arcuate surface of that length which is of reduced radius. Since washer 52 is keyed to collar 45, the rotation of collar 45 (by rotation of button 44 integral therewith) is therefore limited to approximately 180 degrees, the larger portion of washer 52 engaging the stop 49 of the bracket 48 at both ends of this arc. The friction between the interengaging surfaces of the bracket 48 and the friction washer 52 is such as to hold the button 44 (and, therefore, collar 45 and shaft 46) in whatever position to which it is rotated. A spring 53 is disposed about the shaft 46 in engagement with the interior surface of the washer 52, and is compressed by a spring retainer 54 also disposed about the shaft 46. A cam finger 55 is keyed to the shaft 46 and a screw 56 mates with the threaded portion 47 of the shaft 46 to tightly position the retainer 54 and the cam 55 upon the shaft 46. The keyed relationship between the shaft 46 and the cam 55 is such that cam 55 will rotate with rotation of the shaft 46.

A yoke-shaped member 57 is pivoted upon the spaced ears 51 of the bracket 48 and is provided with an aperture 53 through which one end of an adjusting spring 59 is hooked. The bight of member 57, as shown in Figures 2 and 3, is bent so that the lower half thereof projects more inwardly than the upper half. This lower half is bent away from an extended plane of the upper half approximately seventeen degrees. The opposite end of spring 59 is mounted to the threaded portion of an adjusting screw 61. An armature 62 of magnetic material is provided which is bent upwardly (in Figure 4) and provided with a suitable aperture through which the upper end of adjusting screw 61 projects. Armature 62 has integral ears 63 which pivot upon suitable surfaces formed in base 1. As shown in Figures 2 and 3, the pivotal mounting of the armature 62 is such that the armature is adjacent to the non-magnetic inserts 4-1, whereby there is no direct magnetic path between the armature and core 36, inserts 41 providing, in effect, an air gap.

It will be seen that the spring biases the armature 62 in a counterclockwise direction from the position illustrated in Figure 2, and also biases the lower end of yoke 57 inwardly so as to be constantly in engagement with cam 55. Figures 2 and 3 show the cam 55 at the opposite limits of its travel, and the change in the position of the parts associated therewith eifected by change in cam 55 position.

As shown in Figures 2 and 3, armature 62 has threaded therethrough a trip screw 64 and a gap adjustment screw 65. In the assembled device, the gap adjustment screw 65 at its inwardly projecting face engages a trip cross bar 66 of insulating material which is pivotally mounted in inserts 67 disposed in suitable slots at opposite, interior sides of the base 1. Centrally disposed upon the cross bar 66 is a latch strip 68 which, in the closed circuit position of the circuit breaker, as shown in Figure 3, is engaged by and restrains the trip lever 26.

Trip cross bar 66 extends through all three of the compartments in base 1, and is therefore operatively associated with each of the three poles of the circuit breaker. Each of the outer compartments has disposed therein duplicates of the parts 31 through 65, described previously in the description of the central compartment, each of the parts 31 through 65 in the outer compartments being in exactly the same relationship as those in the central compartment, with the exception that the flexible leads are, of course, electrically connected to the particular contact arm in that particular chamber. In each of the outer compartments there is disposed a contact arm 71 through which extends a pivot pin 72 disposed in suitable slots in the insulating base 1. One end of these contact arms are electrically and mechanically connected to flexible leads associated with the trip mechanism disposed in that particular compartment, and the opposite end of each contact arm carries a movable contact 73. The contact arms 71 extend through apertures 74 in an insulating crossbar 75 which extends across all three compartments of the circuit breaker and is fixedly mounted as by rivets 76 to the contact arm 9 disposed in the central compartment of the base 1 so as to be movable therewith. Springs 77 are disposed between the arms 71 and projecting knobs in the slots 74 of the crossbar 75, as shown in Figure 1. It is obvious that any movement of the movable contact arm 9 of the central compartment effects movement of the crossbar '75 which, in turn, carries the contact arms 71 therewith.

In assembling the circuit breaker, all of the parts, with the exception of those numbered 42 through 56, are mounted in position. The gap adjustment screws 65 are set so that the desired relationship, determined by the trip ratings of the breaker, between each armature 62 and the core 36 associated therewith is established. The position of the trip screws 64 relative to the armatures 62 is set by passing sufficient current through each pole of the breaker to seal the armatures 62 against the cores 36. The trip screws 64 are then set in such position that with the armatures sealed against the cores, the trip screws 64 will rotate the crossbar 66 sufiiciently so as to free member 26. The elements 42 through 56 are then placed within the breaker, and the springs 59 are attached to the screws 61. With the buttons 44 set in one extreme position, the screws 61 are connected to the springs 59 such that the circuit breaker will trip at the desired current rating. It will be seen that in the trip mechanism of the present invention the spring 59 determines the bias on the armature 62, tending to rotate it counterclockwise from the view of Figure 2 (and, therefore, determines the current value at which the armature 62 will start to move toward the core 36) and also determines the bias On the trip cross bar 66 tending to rotate it also in a counterclockwise direction, from the view of Figure 2. After all of the tripping mechanisms are assembled and calibrated within the individual compartments, the handle 18 and cover 3 are inserted in position.

Parts, as shown in Figure 3, are in the closed circuit position. Upon manual operation to open the contacts, handle 18 is rotated in a counterclockwise direction to effect rotation of the member 15 in a clockwise direction. When the pivot point 22 between member 15 and the levers 21 passes through the line between the pins 13 and 23, the mechanism passes through the dead center of the line of force of springs 28 and the contact blade 9 is rotated in counterclockwise direction to move the contact 8 to open circuit position. The insulating crossbar 75 carries the contact arms 71, and the movable contacts 73 thereon also to the off position. To close the contacts manually, the handle 18 is rotated in reverse, or clockwise, direction and the mechanism moves through center in the opposite direction to return the contact arms 9 and 71, and movable contacts 8 and 73, to closed circuit position.

Upon automatic operation, the trip cross bar 66 carrying the latch spring 68 will be moved as hereinafter described to release the trip member 26 which swings in a clockwise direction under the bias of the springs 28 and moves the line of force of the springs 28 through center to automatically rotate the contact arm 9 in a counterclockwise direction to open circuit position. The insulating crossbar 75 connected to arm 9, carries the outer contact arms 71 to open circuit position. To restore the circuit breaker after an automatic operation, the handle 18 is rotated to the maximum off" position whereupon the trip member 26 is returned to its latched position as shown in Figure 2.

The operation of the current responsive tripping mechanism of this invention is effected by virtue of excessive current fiow through the coil 35 which establishes a magnetic flux between the core 36 and the armature 62. This flux will cause the armature 62 to rotate in a clockwise To change the current value required to trip the circuit breaker, in each of the three trip mechanisms the button 44 is rotated to effect a change in the bias applied by the spring 59 to the armature 62. In Figure 2 there is illustrated the position of the button 44 and spring 59 in which that spring applies the minimum bias to the armature 62. In Figure 3 the position of the parts is such that the spring 59 applies its maximum bias to the armature 62. It will be seen from a consideration of these two figures, together with the consideration of Figure 5, that both the tension of the spring and the angular relationship between the spring 59 and the armature 62 has been changed. It will be also seen from a consideration of the aforementioned figures that as button 44 is rotated and cam 55 is moved thereby, the configuration of the cam 55 and the yoke 57, and the relationship between these parts, is such that the effective bias applied by the spring 59 to the armature 62 is progressively changed. It will be appreciated that this progressive change in the effective bias applied to armature 62 affords a steplessly, continuously variable and substantially linear relationship between the current value required to efiiect operation of the tripping mechanism and the setting of the button 44.

With the invention shown and described, it will be seen that a very wide range between the minimum and maximum currents required to trip the circuit breaker is possible and, in addition, the device is such as to permit the selection of any current value between the aforementioned maximum and minimum to cause tripping of the circuit breaker. It will further be seen that these desirable features are accomplished with a very compact and relatively inexpensive mechanism. In addition, it is obvious that the device of the present invention may be used with either single or multipole circuit breaker devices.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. In an automatic electric circuit breaker having separable contacts and means including a pivoted armature movable to effect automatic separation of said contacts upon the occurrence of overload current flow through the breaker, means for determining the amount of current required to efiect movement of said armature and consequent separation of said contacts comprising a tension spring, means connecting one end of said spring to said armature whereby said armature is biased toward unoperated position, pivoted means, means connecting the opposite end of said spring to said pivoted means whereby said pivoted means is biased toward said armature, cam means engaging said pivoted means and rotatable in a plane intersecting the plane of said pivoted means where by rotation of said cam means effects pivotal movement of said pivoted means and effects thereby a change in the bias applied by said spring to said armature, said pivotal movement having as its major effect a change in the angular relationship between the bias supplied by said spring and the plane of said armature whereby said change in bias is produced, means operable from the exterior of the circuit breaker to position said cam, and means for maintaining said exteriorly operable means in whatever position it is set.

2. In an automatic electric circuit breaker having separable contacts and means including a pivoted armature movable to effect automatic separation of said contacts upon the occurrence of overload current flow through the breaker, means for determining the amount of current required to effect movement of said armature and consequent separation of said contacts comprising a tension spring, means connecting one end of said spring to said armature whereby said armature is biased toward unoperated position, pivoted means, means connecting the opposite end of said spring to said pivoted means whereby said pivoted means is biased toward said armature, cam means between at least a portion of said pivoted means and said armature engaging said pivoted means and limiting movement thereof under its bias, said cam means being rotatable in a plane intersecting the plane of said pivoted means whereby rotation of said cam means effects pivotal movement of said pivoted means and effects thereby a change in the bias applied by said spring to said armature, said pivotal movement having as its major effect a change in the angular relationship between the bias supplied by said spring and the plane of said armature whereby said change in bias is produced, means operable from the exterior of the circuit breaker to position said cam, and means for maintaining said exteriorly operable means in whatever position it is set.

3. In an automatic electric circuit breaker having separable contacts and means including a pivoted armature movable to effect automatic separation of said contacts upon the occurrence of overload current flow through the breaker, means for determining the amount of current required to effect movement of said armature and consequent separation of said contacts comprising a tension spring, means connecting one end of said spring to said armature whereby said armature is biased toward unoperated position, a yoke, means pivotally mounting one leg of said yoke, means connecting the opposite end of said spring to the other leg of said yoke whereby said yoke is biased toward said armature, cam means between at least part of said yoke and said armature, means mounting said cam in engagement with said yoke and limiting movement thereof under its bias, means for moving said cam in a plane intersecting the plane of said yoke whereby movement of said cam effects pivotal movement of said yoke and effects a change in the bias applied to said armature by said spring, and means for maintaining said cam in whatever position it is set.

4. In an automatic electric circuit breaker, separable contacts, releasable means operable upon release to effect separation of said contacts, an armature pivoted about an axis, means responsive to excessive current flowing through the circuit breaker to attract said armature thereby to turn it about its pivotal axis from an unattracted to an attracted position, means for releasing said releasable means upon said attraction of said armature, a pivoted member turn-able about an axis generally parallel to the pivotal axis of said armature, a tension spring interconnecting said armature and said pivoted member between respective locations on said armature and said pivoted member remote from the respective pivotal axes thereof for biasing said armature toward its unattracted position, said pivoted member and said armature extending from their respective axes in generally aligned and spaced apart relation with the distance between said members being materially less than the length of said spring whereby the line of force of said spring means, when said member is in one turned position and said armature is in its unattracted position, is at a relatively small acute angle with respect to the plane defined by the axis of said armature and the location on said armature at which said spring is attached, and adjusting means engageable with said pivoted member and operable to turn said pivoted member about its pivotal axis into another turned position to alter the length of said spring and concurrently to alter materially the line of force of said spring, whereby the amount of said excessive current required to attract said armature can be varied.

5. A circuit breaker in accordance with claim 4 characterized in that said adjusting means is a cam rotatable about an axis generally normal to the axis of said pivoted member and having an operating surface engageable with said pivoted member in a single plane.

6. A circuit breaker in accordance with claim 5 characterized in that said pivoted member is in the form of a yoke extending in an annular path about the axis of said cam.

7. A circuit breaker in accordance with claim 4 characterized in that the axis of said pivoted member is adjacent the location at which the spring is attached to said armature and said pivoted member extends from 15 2,538,700

its axis in said spaced apart relation toward the pivotal axis of said armature.

References Cited in the file of this patent UNITED STATES PATENTS 678,394 Ghegan July 16, 1901 678,395 Ghegan July 16, 1901 1,713,494 Reichard May 14, 1929 1,724,197 Hartzell Aug. 13, 1929 1,891,702 Allen Dec. 20, 1932 2,426,880 Jackson et al. Sept. 2, 1947 2,491,959 Dyer Dec. 20, 1949 2,494,761 Jackson et al Jan. 17, 1950 Mershon Jan. 16, 1951 

